Method and a machine for manufacturing a sheathed bundle of thread-like elements

ABSTRACT

In the method and the machine for manufacturing a bundle (33) of thread-like elements such as tubes or electric cables of finite length and including at least one junction point for a branch, and in which the elements of the bundle are covered by a tape (31) of thermofusible insulating material wrapped transversely about the bundle with the longitudinal edges (31a, 31b) of the tape being united by welding, two rows each comprising a plurality of wheels (9 to 14) for driving the bundle (33) and the tape (31) are provided, the wheels pressing against the tape, a V-shape being previously imparted to the tape by a guide situated upstream from the wheels, said rows of wheels defining between them a through path (18) for the bundle, the path being upwardly open and passing successively beneath a first horizontal guide (23) for folding down one of the sides of the V-shape against the bundle, beneath a nozzle (36) for blowing hot air into the angle formed between the folded-down side (31a) and the non-folded-down side (31b) of the V-shape, and beneath a second horizontal guide (25) for folding the second side (31b) of the V-shape down onto the already-folded-down first side (31a).

The present invention relates to a method and to a machine for quicklyand cheaply manufacturing a bundle of thread-like elements where thebundle includes at least one branch such as the harnesses of tubes orelectric cables commonly to be found in motor vehicles.

In the motor industry, electrical wiring is generally performed bypreparing one or more bundles of wires on an assembly jig, in holdingthe wires together by means of tape or of a split sheath of plasticsmaterial, and in covering the assembly with a polyurethane foam or withan adhesive baize structure.

The sheathing or taping has the essential function of imparting acertain amount of cohesion to the bundle so as to make it easy toinstall along the structure of a vehicle, and simultaneously it forms aflexible covering that absorbs vibration and damps shocks between thebundle and the bodywork, which shocks would otherwise generate noise.

Such bundles are generally built up manually, taking a large amount oftime, and the materials used are poor at withstanding aging or thesevere environmental conditions that exist in the engine compartment ofa motor vehicle.

Several methods exist for making a sheath around a bundle of electriccables, and one of them consists in enclosing the bundle of cables in atape by wrapping the tape transversely to itself around the bundle, andthen uniting the two lateral edges of the tape. That method is used, inparticular, for applying thermal insulation to pipework. The problemwhich is poorly solved by known apparatuses and methods is the problemof allowing branches of the bundle to pass through the sheath.

One way of overcoming this difficulty, that has been proposed in thepast but that is not satisfactory, is to place a sheath on branchingbundles by building up the bundles on a board having means fordetermining the shape of each of the wires making up the bundle; theboard including sheet material that is cut out to the shape of thebundle and its branches; the wires being placed on the sheet in theirfinal configuration; the entire structure being covered by the samesheet material cut out in similar manner; and the wires of the bundlebeing enclosed between these two cut-out sheets that are united alongtheir edges by gluing, welding, or by any other means. That method islabor-intensive and does not provide a satisfactory technique forrapidly sheathing bundles that include branches.

The invention differs from prior techniques of sheathing a bundle ofcables or tubes by the way in which the problem to be solved is takeninto consideration. A bundle including branches can be considered ascomprising a plurality of bundles that are to be combined, which bundlescan be treated successively providing it is not necessary to close thesheath at the junction point of each branch. Accepting such imperfectsheathing goes against the prejudices of those concerned with sheathingand insulation, but for the special case of cable harnesses and the likein motor vehicles, sheathing is not there to protect the wires of aharness hermetically, but is essentially used for lagging purposes inorder to avoid noise. Thus, accepting small imperfections in thesheathing of cable harnesses in motor vehicles does not have anyundesirable consequences on the main technical effect that is desired.

Thus, in a first aspect, the present invention provides a method ofmanufacturing a bundle of thread-like elements such as tubes or electriccables of finite length, in which the bundle includes at least onejunction point for a branch, and in which the thread-like elements of abranch are enveloped in a plane thermofusible insulating material thatis wrapped transversely about the elements and that has its longitudinaledges united by welding.

According to the invention, when a bundle has a branch, each of thebranches of the bundle is sheathed in succession by means of arespective tape that is wrapped transversely around the thread-likeelements composing said branch, and the edges of the tape are united bywelding except at the location of junction points between branches. Abranching bundle sheathed in this way thus leaves uncovered the root ofeach branch on the parent branch from which it stems. This apparentimperfection in the sheathing has no harmful effects in particular onthe sound-reducing qualities of the bundle made in this way. Incontrast, the method implemented makes it possible to achieve asignificant saving in the time and cost of sheathing operations, andalso makes it possible to automate them.

In a particular implementation of the invention, the heat for welding isprovided by blowing hot air against the outside face of one margin ofthe tape and against the inside face of the opposite margin while saidmargins are moving past the flow of hot air and while they are beingheld so as to form a groove, welding subsequently consisting in pressingone of the margins heated in this way against the other. The use of ahot air flow is advantageous when it comes to flexibility ofimplementation.

In the above implementation, it is preferable to regulate the heatapplied by diverting an adjustable fraction of the flow of hot air thatwould otherwise be directed into the angle of the above-mentionedgroove. This disposition makes it possible to use a source that producesheat at a constant rate and is thus easy, regular, and reliable inoperation, with the heat required for welding thus being regulatedindependently of the operation of the primary source and being easilyservo-controlled, e.g. to the speed at which the bundle and its sheathis moving through the flow of hot air.

When going past branching points, additional hot air flow is diverted,or the entire flow of hot air may be diverted.

In a second aspect, the present invention provides a machine formanufacturing a bundle of thread-like elements such as tubes or electriccables of finite length, the bundle including at least one junctionpoint for a branch, and the elements of the bundle being covered in atape of thermofusible insulating material wrapped transverselytherearound with the longitudinal edges of the tape being united bywelding, which machine includes a welding head comprising two rows eachof a plurality of drive wheels for simultaneously driving the bundle andthe tape, a V-shape previously being imparted to the tape by a guidesituated upstream from said wheels, said rows of wheels defining betweenthem a through path for the bundle, which path is upwardly open andpasses successively beneath a first horizontal guide for folding downone of the sides of the V-shape against the bundle, beneath a nozzle forblowing hot air into the angle formed between the folded-down side andthe non-folded-down side of the V-shape, and beneath a second horizontalguide for folding down the second side of the V-shape against thealready folded-down first side. With this machine, it will be understoodthat the tubular sheath is formed by welding together the twooverlapping opposite margins of a tape. In the context of the invention,such welding by means of hot air (which is known per se) has theadvantage of being easy both to adjust and to servo-control firstly tothe speed at which the bundle travels through the welding head, andsecondly to the need to interrupt such welding when going past thejunction points of branches that branch off from the branch that isbeing sheathed.

For the purpose of going past the junction points, the horizontal guidesare retractable against a return member tending to maintain them in theoperating position. Such retraction is performed in a plane parallel tothe travel direction of the bundle.

Of the other characteristics of the invention, particular mention may bemade of a characteristic relating to the hot air blast nozzle whichincludes a vent outlet upstream from its end overlying the travel path,and the through section of the vent outlet is adjustable as a functionof the speed at which the bundle is driven by the wheels. The blastnozzle may include a second vent outlet whose through section is eitheropened or closed depending on whether a junction point of the bundle ispresent or absent on the travel path.

Other characteristics and advantages of the invention appear from thefollowing description of an embodiment thereof.

Reference is made to the accompanying drawings, in which:

FIG. 1 is an elevation view of a machine of the invention;

FIG. 2 is a plan view of the machine and in particular of the weldinghead that it uses;

FIG. 3 is a section view on line III--III of FIG. 1 through the weldinghead of the machine of the invention in a variant embodiment thereof;

FIGS. 4A-4F are a diagram showing the method implemented for twodifferent sizes of sheathed bundle; and

FIG. 5 is a diagrammatic section view through a hot air blast nozzleimplemented in the invention.

In the figures, it can be seen that the machine comprises a stand 1which may be constituted by a workbench, for example. The stand includestwo vertical support elements 2 and 3 which slidably receive rods 4 and5 that are parallel to each other and to the workbench, which rods areinterconnected at one of their ends by means of a horizontal crossbar 6whose midpoint is pivoted to the support element 2. The rods 4 and 5form a support for two blocks 7 and 8, each block forming the supportfor a group of three roller wheels 9, 10, and 11 for the block 7, and12, 13, and 14 for the block 8. The block 7 has one of its ends securedto the rod 4 while its other end is slidably mounted on the rod 5,whereas the block 8 is secured to the rod 5 and has its other endslidably mounted on the block 4. Beneath its bottom face, each blockalso supports drive pulleys for each of the sets of wheels carriedthereby, said drive pulleys, referenced 15 in FIG. 3, are coupledtogether by means of belts, and they are coupled to a drive shaft 16which is itself coupled to drive means 17 disposed beneath the stand 1.The shaft 16 is parallel to the rods 4 and 5 so that the belt whichconnects it to the sets of pulleys 15 of the blocks can slide along saidshaft 16 when the blocks move along the rods 4 and 5.

The two groups of roller wheels 9, 10, 11 and 12, 13, 14 define betweenthem a through path 18 of adjustable width. As shown in FIG. 2, thethrough path 18 is at its minimum width. If the crossbar 6 is pivotedclockwise about its pivot on the support 2, then the rod 5 is pushed tothe right together with the block 8 that is coupled thereto, while therod 4 is pulled to the left together with the block 7 which is coupledthereto. A spring 19 coupled between the support element 2 and thecrossbar 6 urges the two blocks 7 and 8 towards each other so as tominimize the width of the path 18. In FIG. 2, the lefthand end of therod 4 has a rack 20 suitable for co-operating with a catch lever 21 soas to oppose the drive from the spring 19 when the catch lever engagesin one of the notches in the rack 20, thereby enabling the width of thepath 18 to be maintained at a size greater than its minimum size. Thisdisposition makes it possible to hold the path 18 at its maximum widthso as to facilitate inserting the bundle to be sheathed between the twogroups of wheels, and once the bundle has been inserted, the rod 4 canbe released, thereby enabling the spring 19 to cause the wheels; toexert constant pressure on the bundle, regardless of the size of thebundle.

A support 22 is also secured to the rod 4 for an upper guide 23 thatextends over the first wheel 12 and over the through path 18. It will beunderstood that this guide which is secured to the rod 4 remainsstationary relative to the block 7 and thus extends over the entirewidth of the path 18 whatever that width may be.

Similarly, a support 24 for another upper guide 25 is secured to the rod5, the guide 25 extending over the wheel 11 carried by the block 7.

Each of the guides 23 and 25 is constituted by a horizontal fingercarrying a downwardly-extending end catch 26, the finger being pivotedto the corresponding support 22 or 24 about a vertical axis 27 so as toenable it to retract when a rigid obstacle travelling along the path 18and projecting above the level of the wheels 9 to 14 goes past, wheresuch an obstacle may be a branch of the bundle. Such retraction thustakes place about the axes 27 against respective return springs 28 forreturning each guide to its position where it extends over the throughpath 18.

The direction in which a bundle to be sheathed travels between the twoblocks of wheels is indicated by arrow A in FIG. 2, with the inletwheels thus being the wheels 9 and 12. Upstream from these inlet wheels,the machine includes a guide 29 having a V-shaped opening 30 serving toraise each of the edges of a tape of sheathing material 31 that isinserted on the through path in direction A. The guide 29 includes atongue 32 extending between the wheels 9 to 14 and forming the bottom ofthe through path 18.

FIG. 3 shows this tongue 32 as being inclined so that the driving actionof the wheels on the bundles 33 passing along the path 18 includes ahelical component tending to press the tape 31 around the thread-likeelements making up the bundle 33 to be sheathed and that are placed inthe path 18 and are received in the bottom of the V-shape formed by thetape 31 whose edges are raised by the guide 29. Naturally, the tongue 32could extend horizontally between the wheels if this effect oftightening the sheath around the bundle 33 of thread-like elements isnot desired.

The height of the tongue 32, and thus of the bottom of the through path18, may be adjusted automatically as a function of the width of thethrough path. To this end, the guide 29 may be vertically adjustable,e.g. by means of camming surfaces 34 (oblique slots) co-operating withpositioning studs 35 secured to the wheel-support blocks 7 and 8 so thatmoving the blocks apart causes the guide 29 to be moved downwardsrelative thereto.

Between the two horizontal guides 23 and 25, the welding head comprisesa hot air blast nozzle 36 disposed above the wheels and shown in sectionin FIG. 5. The nozzle 36 includes a first vent 37 suitable for beingclosed to a greater or lesser extent by a piston 38 depending on how farthe piston is engaged in the nozzle 36, and a second vent 39 suitablefor being closed to a greater or lesser extent by a sleeve 40 that islikewise displaceable along the nozzle 36. The hot air feed for thenozzle 36 comes from a chamber 41 at the outlet from a constant flowsource. The chamber 41 communicates with the inside of the nozzle 36 viaan orifice 42, so the first vent 37 constitutes a diversion path for thehot air before it even enters the orifice 42. The position of the piston38 may be servo-controlled to the speed at which the bundle is beingdriven, i.e. to the speed of rotation of the drive means 17, whereas theposition of the sleeve 40 may either be a position for closing the vent39 or else a position for opening said vent completely, depending onwhether or not a branch 43 is detected on the path 18 where the bundlepasses between the wheels.

It will also be observed that in order to disengage the path 18completely so as to provide access to said path from above even at theguides 23 and 25, the supports 22 and 24 for said guides are made up oftwo portions that are hinged to each other about respective horizontalaxes 44 enabling the guides 23 and 24 to be tilted away from the path 18about said axes 44 against respective return springs 45 tending to putthe guides 23 and 25 above the path 18.

In order to sheath a bundle 33 of thread-like elements by means of tape31 wrapped around the bundle so that its edges are united, the method ofthe invention is as follows.

The end of the tape 21 is engaged in the guide V-shape 29 after theguide blocks 7 and 8 have been moved apart and the horizontal guides 23and 25 have been raised by tilting their supports about the axes 44. Theend of the bundle 33 to be sheathed is placed in the V of tape as formedin this way and which extends at least as far as the first pair ofwheels 9 and 12, after which the wheels are urged against the sides ofthe V-shape and the horizontal guides 23 and 25 are brought back downover the through path 18. Depending on the number and the diameter ofthread-like elements that are to be sheathed, the section of the bundlemay vary between extreme sizes (e.g. 8 mm and 32 mm) as shown in FIGS.4A-4F. Naturally, the width of the tape is adapted to the size of thebundle 33 to be sheathed. FIG. 4A shows the position taken by the tapeand by the bundle beneath the guide 23 which serves to fold one of thesides of the tape V-shape over the bundle. The wheels 10 and 13 situatedin the center of the welding head allow access to the inside of thegroove (or pseudo-groove) formed by the two edges 31a and 31b of thetape, one of which edges is folded down on the bundle while the otheredge extends up the wheel 10. The nozzle 36 blows hot air into the angleof this groove for the purpose of partially melting the outside surfaceof the edge 31a and the inside surface of the edge 31b. Under drive fromthe wheels, the bundle continues to move so as to reach the third set ofwheels 11, 14, where the bundle passes beneath the second horizontalguide 25 which serves to fold the edge 31b down against the edge 31a sothat their facing and partially-melted surfaces are welded together.

If the bundle 33 has a branch 43, then the branch is guided so as toextend vertically upwards between the wheels of the welding head, andwhile the branch 43 is going through, firstly the sleeve 40 opens thevent 39 so as to divert a major portion of the hot air that wouldotherwise be blown against the bundle, and secondly the branch actsmechanically on the horizontal guides 23 and 25 which retract in ahorizontal plane about their respective axes 27 against their returnsprings 28. Once the branch 43 has gone through, the guides return totheir original positions, and tubular sheathing can continue on thenon-branching portion that follows the branch.

In an automated version of the machine, it is quite possible to ensurethat detection of a branch in the vicinity of the drive wheels serves,for example, to slow down the drive speed and thus cause the piston 38to be displaced so as to open the vent 37 to a greater or lesser extent,thereby diverting a portion of the hot air flow used for partiallymelting the edges of the tape. Once the branch has gone past, drivespeed can return to a higher value and the hot air blast rate can berestored.

With the machine of the invention and in application of the method ofthe invention, a complex bundle is processed by successively sheathingfirst a main branch, and then each of the branches branching therefrom..The bundle provided by the invention naturally has zones that areuncovered at the location of each junction point, but this does notdegrade the qualities desired from a sheathed bundle. Nevertheless, itis possible to patch the bundle manually so as to close up thenon-sheathed gaps, but this increases manufacturing costs.

The machine of the invention has been described in the context of aninstallation that is stationary, with the bundle being driven throughit. It is quite possible, without going beyond the scope of theinvention, for the welding head to be carried by a hand tool that isdisplaced along a cable bundle which is held stationary via its ends andalso at certain other locations, in particular in the vicinity of itsjunction points.

We claim:
 1. A method of manufacturing a bundle of tubes or electriccables of finite length, in which the bundle includes at least onejunction point for a branch, and in which the tubes or electric cablesof the bundle are enveloped in a plane thermofusible insulating materialthat is wrapped transversely about the elements and that has itslongitudinal edges united by welding performed by application of heat,except at locations of junction points with each branch, the methodbeing characterized in that each branch of the bundle is sheathed insuccession by means of a respective tape that is wrapped transverselyand is closed around the tubes or electric cables constituting thebranch except at the location of a part of said branch which is adjacentto a respective one of the junction points.
 2. A method according toclaim 1, characterized in that the heat for welding is provided byblowing hot air against an outside face of one margin of the tape andagainst an inside face of an opposite margin while said margins aremoving past a flow of hot air and while they are being held so as toform a groove, welding subsequently consisting in pressing one of themargins heated in this way against the other.
 3. A method according toclaim 2, characterized in that the heat applied is regulated bydiverting an adjustable fraction of the flow of hot air that wouldotherwise be directed into an angle of the groove.
 4. A method accordingto claim 3, characterized in that whenever a branch goes past,additional hot air is diverted.
 5. A machine for manufacturing a bundleof tubes or electric cables of finite length, the bundle including atleast one junction point for a branch, and the elements of the bundlebeing covered in a tape of thermofusible insulating material wrappedtransversely around the bundle with longitudinal edges of the tape beingunited by welding, the machine being characterized in that it includes awelding head comprising two rows each of a plurality of drive wheels fordriving the bundle and the tape against which the wheels bear, a V-shapepreviously being imparted to the tape by a guide situated upstream fromsaid wheels, said rows of wheels defining between them a through pathfor the bundle, which path is upwardly open and passes successivelybeneath a first horizontal guide for folding down a first side of theV-shape against the bundle, beneath a nozzle for blowing hot air into anangle formed between the folded-down first side and a non-folded-downsecond side of the V-shape, and beneath a second horizontal guide forfolding down the second side of the V-shape against the alreadyfolded-down first side.
 6. A machine according to claim 5, characterizedin that the horizontal guides are retractable when branches of thebundle go past, the guides being retractable against return memberstending to keep them in an operating position.
 7. A machine according toclaim 5 characterized in that a width of the through path for the bundleis adjustable, each row of wheels being secured to a respective supportblock that is displaceable transversely relative to the through path ofthe bundle against a return member tending to minimize the width of thethrough path.
 8. A machine according to claim 5, characterized in thatthe through path is delimited by a bottom that slopes relative to thedirection of the wheel axes.
 9. A machine according to claim 5,characterized in that the upstream guide for imparting a V-shape to thetape is adjustable in height as a function of the width of the throughpath.
 10. A machine according to claim 5, characterized in that thefirst and second horizontal folding-down guides are retractable betweentheir operating positions over the through path for the bundle andpositions that disengage top access to the path for insertion of a newbundle to be sheathed.
 11. A machine according to claim 5, characterizedin that the hot air blast nozzle includes a vent outlet upstream fromits end over the through path, the section of the outlet beingadjustable as a function of the speed at which the bundle is driven bythe wheels.
 12. A machine according to claim 5, characterized in thatthe hot air blast nozzle includes a vent outlet upstream from its endover the through path, with the section of said outlet being opened orclosed depending on whether a branch of the bundle is present or absentin the through path.